of the Bulgarian 4th Army while the main Bulgarian forces attacked the flanks of the Greek Army in an effort to completely encircle it. The operation began on 15 July with successful Bulgarian advances on both flanks and in the center. General Vasil Kutinchev, who replaced general Ivanov as commander of the 2nd Army on 16 July, used the situation to retake height 1378 in the center of the front and exerting pressure on the Greeks who were transferring part of their forces from the center in order to strengthen their flanks. The greatest threat for the Bulgarians however came from the Greek 2nd and 4th divisions which attacked between 15 and 17 July the right wing of the Second Army in an effort to utilize a gap that had opened between it and the 4th Army and eventually join hands with the Serbians at Tsarevo Selo. The Greek advance, however, was halted and the reorganized right wing of the Second Army continued its attacks against the left wing of the Greeks in the Kresna Gorge. The Serbians also tried to assist but their attacks were repulsed by the 7th Rila Division of the Bulgarian 4th Army. King Constantine realized that his army was placed in a very difficult situation and his so far uncompromising attitude towards Bulgarian offers for a ceasefire gave way to a more yielding attitude. He admitted that his forces were reaching the limits of their morale physical endurance and asked his prime minister Eleftherios Venizelos to reach a ceasefire agreement as soon as possible. By 17 July, the Bulgarians had achieved success with their right flank advancing with between 15 and 18 kilometers in three days and the Greeks heavily engaged in the center and on their right flank. The advance was to continue on 18 July but the Greek king managed to obtained the ceasefire he and the Bulgarian delegation in Bucharest desired before any further military actions were undertaken. The army was demobilized on 29 July, one day after the signing of the Treaty of Bucharest. First World War Only two years after the end of the Second Balkan War Bulgaria entered World War I on the side of the Central Powers. The Bulgarian Army began mobilizing on 9 September(23 September) 1915 and the three field armies were once again activated. Serbian Campaign On 24 August(6 September) 1915 at the German military headquarters